1. Field of Invention
The invention relates to vehicle suspension systems in which a suspension for a vehicle wheel is associated with a drive unit.
2. Description of Related Art
Vehicles usually have a prime mover or power unit which drives two or more wheels of a vehicle. However, individual drive units for hydraulically or electrically driving the individual wheels have been used.
The invention provides an improved vehicle suspension system incorporating a drive unit. According to the invention, the vehicle suspension system comprises a suspension unit for at least one wheel, a drive unit for the wheel and transmission means between the drive unit and the wheel. The suspension unit is pivotally attached to the chassis, and pivotally receives the wheel. The transmission means accommodates pivoting of the suspension unit relative to the chassis during operation of the vehicle.
In various exemplary embodiments, the drive unit is a motor arranged to drive the associated wheel and the transmission means includes a drive shaft, step down gearing, and a right angle gear box at the wheel.
In other exemplary embodiments, there is a drive unit for each of a pair of wheels of the vehicle, and control means for controlling the driven wheels to obtain the desired drive characteristics of the vehicle, whereby the driven wheels may be driven at the same or different speeds according to predetermined driving parameters of the vehicle, for example, travelling in a straight line or travelling around bends.
Other exemplary embodiments include two suspension units mounted on each end of a cross beam, which is mountable transversely on the vehicle chassis. In these embodiments, a drive motor for each drive wheel is mounted on the chassis in association with each suspension unit to drive the associated wheel. For a rear wheel drive vehicle, the cross beam may be mounted towards the rear of the vehicle and under the chassis.
In other exemplary embodiments, the drive motor or motors of the vehicle are electric motors and the step down gearing is mounted adjacent the associated driven wheel. The motors may be mounted above the cross beam and at or above the lower level of the chassis, whereby the transmission from the motor has a downwardly extending drive shaft. Constant velocity joints may be provided towards each end of the drive shaft to accommodate movements of the wheel.